Co-authored-by: Denny Sun <dennys@microsoft.com>

We do ensure at least one string is present though, otherwise conflicts arise

This fixes a slight regression when parsing a preproc function definition using division operators

`a *= b != c ? d : e;` is parsed incorrectly as a result

This reverts commit eb6649e0c2.

Previously, pointers were associated with the function identifier, now they're associated with the return type

This resolves conflicts with declarations that can be interpreted as binary_expressions

* feat: allow identifiers in string concatenations

Resolves errors in strings of the form:

   ("failed in line %" PRIdLINENR)

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Co-authored-by: Lewis Russell <lewis6991@gmail.com>

_Generic is a C11 feature, __restrict__ and _Noreturn were added to type_qualifiers

It's allowed in gcc and clang

According to cppreference, identifiers are `(XID_Start | '_')
XID_Continue*`, which is the case as of C++23 and C2x. I have confirmed
this myself with the drafts of C++23 and C2x.

https://en.cppreference.com/w/cpp/language/identifiers

Clang indeed implements identifiers as `(XID_Start | '_') XID_Continue*`
in C++ mode and C2x mode, with a slight extension to the character set
to include some extra math characters:
231992d9b8/clang/lib/Lex/Lexer.cpp (L1517-L1530)